Conveyors typically comprise a bed that is bounded by two vertical opposing side walls, a drive pulley mounted for rotation at one end of the conveyor, a take-up pulley mounted for rotation at the opposing end, and an endless belt that is oriented horizontally and that loops around each of the pulleys. It is often necessary to adjust the alignment of the take-up pulley to track the conveyor belt or to otherwise adjust the tension in the belt. U.S. Pat. No. 3,832,910 entitled TELESCOPIC BELT TIGHTENER and issued to Bryant is an example of a belt-tightening mechanism used to make such adjustments to the take-up pulley. In the Bryant patent, the belt tightener includes an outside tube fixed to mounting brackets and having an end plate, and an inside tube telescoped in the outside tube with one end of the inside tube having a plate which is connectable to a bearing block for the shaft that supports the endless belt. An adjusting bolt extends through the end plate of the outside tube and further extends into the inside tube, the adjusting bolt being threadably received by a nut welded to the other end of the inside tube. The adjusting bolt is used to adjust translation of the plate and bearing block.
In such a configuration, forces of tension and compression are distributed in a complex manner along the length of the tube and through the mounting brackets. Further, such a configuration requires welding of the brackets and end plate to the outside tube. Because of the complex forces acting through the tube and the brackets, it is necessary to ensure that each of the brackets and the end plate are properly welded to the outside tube.
Accordingly, a need has existed for a linear actuator that adjusts the orientation of the take-up pulley and eliminates the complex forces acting thereupon. A need has further existed for such a linear actuator that requires less welds, thus reducing the points of possible failure and reducing the time necessary to manufacture such linear actuator.